Symptoms Of A Bad Crankshaft Pulley


Have you ever considered the effects of a defective crankshaft pulley on your vehicle? Well, it goes without saying that they’re disastrous.

When a crankshaft pulley fails (or the timing belt due to a badly maintained crankshaft pulley), the timing of the engine will completely thrown off. This in-turn will cause vibrations, irregular engine idles, and possibly even noise.

Continue reading below to find out how you can recognize the warning signs and repair a broken crankshaft pulley.

What Is The Function Of A Crankshaft Pulley?

The crankshaft pulley is tasked with two simple but vital functions:

  • Managing the time between the crankshaft and other engine components

Without this vital connection, pistons cannot be brought into alignment with camshafts, cam followers, valves, and engine disassembles.

  • Absorbing vibrations caused by the crankshaft

Without the rubber dampening layer contained in a TVD, vibrations of the engine would be transmitted to the remainder of the engine, resulting in continuous wearing and eventual engine failure. 

Common Symptoms Of A Bad Crankshaft Pulley

Naturally, a vehicle will exhibit signs of deterioration if any of its components fail. Following are the signs of a failing crankshaft pulley.

Essentially, everything along the belt will be affected.

Engine Vibration

The crankshaft pulley in your car is tasked with keeping the crankshaft and the rest of the engine vibration-free. When the pulley begins to fail, engine vibrations grow rapidly. These vibrations are destructive to the engine’s accessories, the crankshaft, and other elements of the system.

Although bad motor mounts could also be responsible for engine vibrations, make sure to check those too.

Irregular Engine Idle

As the engine idles, the crankshaft pulley is exposed to a high degree of tension. Crankshaft pulleys that are defective can cause a rough engine idle. Examine the crankshaft pulley in case the engine of your vehicle idles irregularly but there are no misfires or other combustion issues.

Dead Alternator

Whilst the alternator is crucial for charging the battery and running accessories, the crankshaft pulley provides power to the alternator. If the crankshaft pulley fails, the alternator will cease to operate and generate electricity.

Noise From The Engine

One of the signs of a failing crankshaft pulley is very loud engine noise. When there is engine vibration, your engine will make a lot of loud noises. As you shift into higher gear, the sounds will start to pop. If the noise increases in volume or becomes extremely loud, you should not attempt to drive your vehicle and instead immediately have a mechanic inspect it for a possible crankshaft pulley failure.

Drive Belt Damage

A defective crankshaft pulley might also cause the drive belt (also called a serpentine belt) to be misaligned, which in turn damages the belt’s edges. This might also damage to the non-metallic pulleys, idle rollers and potentially everything along the belt.

Less Common Symptoms:

There are also less common, but still possible, symptoms that would manifest after a very long time of driving with a bad crankshaft, to the point where it severely damages the serpentine belt and in turn, causes everything that runs along the belt to cause havoc.

Transmission System Trouble

If the engine vibrates excessively, these vibrations can cause transmission damage. Once the transmission bearings, gears, and input shaft have been compromised by the strong vibrations, a new set of symptoms will eventually manifest. You will experience transmission fluid leakage, and gear changing issues, among others.

Battery Light

If the rubber or separating material fails, the crankshaft pulley will eventually fail. The inner component will detach from the outer component that contacts the driving belt. As soon as the drive belt stops turning, the remainder of the powered accessories will stop functioning.

The alternator, connected by a drive belt, will cease to spin and will be unable to charge the battery, causing the battery indicator to light on the instrument cluster.

Power Steering Pump Failure

The crankshaft pulley drives the power steering pump of the vehicle. This essential component pumps hydraulic power into the engine so that the steering functions properly. When the power steering fails, controlling the vehicle will need significantly more effort.

Damaged Internal Engine Parts

Long-term engine vibration will damage the internal engine parts such as the crankshaft bearings, which is a problem that you do not want to deal with. The input shaft, bearings, and gear are all susceptible to this damage.

AC Compressor Failure

The AC Compressor, also driven by the drive belt, will cease to function if the crankshaft pulley breaks.

Mistimed Ignition 

Without a functional crankshaft pulley, the ignition timing of your car will be messed up. This improper ignition timing is caused by an irregular signal from the crankshaft sensor, which is a result of the inability of the crankshaft pulley to regulate the component. The condition prevents your automobile from starting.

The automobile will crank, indicating that the engine is attempting to start, but without the correct timing, the engine components cannot accomplish spark ignition.

Consequences Of A Crankshaft Pulley Failure

When the crankshaft pulley fails or the timing belt breaks as a result of a badly managed crankshaft pulley, the engine’s timing is thrown entirely out of whack. In such a fine system, even a rotation or movement of a few millimeters can cause complications.

When Should A Crankshaft Pulley Be Changed?

You may be surprised to hear this but a crankshaft pulley is constructed to outlast the engine. However, the rubber ring can become broken owing to higher temperatures, wear and tear, and exposure to coolant or engine oil. The problem also occurs when you purchase a new one that has been lying on the warehouse shelf for years.

Among the indications that your crankshaft pulley requires replacement are:

  1. The engine is noisy, and you can feel vibrations emanating from it.
  2. The slippage of the pulley belt may cause your car to misfire or backfire.
  3. The ignition timing will be faulty.
  4. The vehicle cannot be started in any way.

Cost Of Replacing A Faulty Crankshaft Pulley

Now to the numbers: How much does it cost you for replacing a faulty or failed crankshaft pulley? It costs between $300 and $400 to replace your faulty crankshaft pulley, depending on the manufacture, model, and kind of vehicle plus added labor fees. The average price of a brand new crankshaft pulley is around 200-300 USD, and the average labor cost is $150.

How To Fix A Failed Crankshaft Pulley?

If you wished to change the crankshaft pulley on your own, the task is not difficult. Additionally, you could save money by reducing labor expenses.

Here are a few basic tips on how to accomplish it yourself:

  1. Remove all driving belts from the engine.
  2. Remove the bolt from the crankshaft pulley. You will need a (pulley) holder plus an impact wrench with a high torque rating.
  3. Get rid of the old and faulty pulley.
  4. Install the new pulley for the crankshaft.
  5. Replace and tighten the bolts..
  6. Install all of your engine’s drive belts again.

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